FRONT-END IN GAAS

The use of GaAs MESFETs in the realization of low-noise preamplifiers for particle detectors are analized in this paper. Fundamental properties of GaAs are reviewed. The low ionization energy of dopant impurities allows operation at cryogenic temperatures. The high electron mobility permits to obtain high gain-bandwidth products with low power dissipation. Voltage-sensitive preamplifiers for 4 K operation have been developed and are presently used with bolometric particle detectors. Charge-sensitive preamplifiers for liquid calorimetry have also been developed and are used for the readout of the Accordeon LAr calorimeter prototype. A version based on a monolithic array of MESFETs was tested as a first step towards a monolithic preamplifier version. So far, hybrid techniques have been used for the preamplifier manufacturing with a very high yield.